The field of this invention relates to methods for removal of screen after a gravel packing operation so that production from another or lower interval can commence.
Occasionally well strings get stuck during drilling or completion activities creating a need to work them loose. Vibratory devices have been used to loosen stuck tubulars downhole. Several examples of such devices are U.S. Pat. Nos. 4,299,279; 5,803,182; 6,182,775; 6,009,948; 5,234,056; 4,667,742; 4,913,234 and 4,236,580. Vibratory devices have been used in conjunction with gravel packing operation to help disperse the sand around the outside of the screen and into the previously perforated casing. This technique is shown in FIG. 53 of U.S. Pat. No. 5,309,405. In situations where further production is desired from a zone beyond a gravel packed screen, it was in the past necessary to either mill out the screen or to start a lateral above it and otherwise isolate that branch of the well. Other techniques involved trying to wash over the screen and lift it out. The problem with the latter technique is that the gravel outside the screen would firmly wedge it in place so that the screen would not break loose within the pulling limits of the string or the surface equipment. Milling the screen created a debris removal issue and drilling a sidetrack was a lengthy process involving sophisticated equipment and was very costly.
The methods of the present invention address the shortcomings of the prior techniques to provide a technique that will simply get the screen out. The wedged screen is perforated to allow gravel to flow into its interior. A combination of vibration and circulation or reverse circulation is utilized after the screen is isolated in the well to get the gravel to flow and the screen to let go. The screen, being retained by the bottom hole assembly can be subsequently retrieved with minimal damage to the well. Further completion work can go on beyond the former screen location. These methods will be more readily understood by those skilled in the art from a review of the description of the preferred embodiment and the claims, which appear below.
A method of removing a gravel packed screen to reach another zone is described. The method involves a bottom hole assembly comprising an isolation device for the screen and a tool to latch on to it. A perforating gun is shot off to put holes in the screen to allow gravel to come through. A flow through a reversing valve is initiated to urge the gravel into the newly perforated screen while a vibrator shakes the screen and stimulates gravel flow through the screen. Alternatively, the screen is not isolated and a reverse circulation from the surface in conjunction with vibration urges the gravel to flow through the screen and out through the tubing supporting the bottom hole assembly.